EDP Sciences
Free access
Volume 433, Number 1, April I 2005
Page(s) 79 - 86
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20034537

A&A 433, 79-86 (2005)
DOI: 10.1051/0004-6361:20034537

Asymmetrical structure of ionization and kinematics in the Seyfert galaxy NGC 5033

E. Mediavilla1, A. Guijarro2, A. Castillo-Morales3, J. Jiménez-Vicente3, E. Florido3, S. Arribas4, B. García-Lorenzo1 and E. Battaner3

1  Instituto de Astrofísica de Canarias, Tenerife, Spain
    e-mail: emg@ll.iac.es
2  Centro Astronómico Hispano Alemán, Almería, Spain
    e-mail: aguijarr@urg.es
3  Dpto. Física Teórica y del Cosmos, Universidad de Granada, Spain
4  Space Telescope Science Institute, Baltimore, USA

(Received 18 October 2003 / Accepted 29 November 2004)

We present integral field spectroscopy of NGC 5033, a low luminosity Seyfert galaxy. The observations were made with INTEGRAL, a fiber based system operating at the WHT. The intensity map of the H$\beta$ emission line represents a spiral or ring-like pattern of HII regions. On the contrary, the [OIII] intensity map morphology is markedly anisotropic. The strong morphological differences imply that the [OIII] emitters represent highly ionized gas illuminated by the central source. The [OIII] map morphology is compatible with a biconical structure of ionization induced by strong extinction in the galaxy disc that also obscures half of the spheroidal stellar bulge. We identify the spectrum corresponding to the Seyfert 1 nucleus from the presence of H$\beta$ broad emission lines. This spectrum is located in a region where strong extinction is expected but exhibits the bluest spectral energy distribution. The Seyfert 1 nucleus seems to be offcenter with respect to the stellar rotation center. This result has been also found in other Seyfert galaxies and interpreted in terms of a past merger. The offcentering could indicate the presence of nonsymmetric departures in the gravitational potential which could be fueling the active nucleus. The kinematics of the [OIII] emitters show important deviations at a kpc scale with respect to the stellar velocity field and show features related to the asymmetrical morphology of the high ionization region.

Key words: galaxies: active -- galaxies: individual: NGC 5033 -- galaxies: kinematics and dynamics -- galaxies: spiral -- galaxies: Seyfert -- galaxies: nuclei

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